It is important, I think, to prioritize one's mental health when in situations like you describe.

I don't see how it could help your grandson if you have a breakdown.

I used to put everyone else first in my life, had a breakdown, ended up in a mental hospital and even after release was totally dysfunction for three years.

I think your relatives have unrealistic expectations when it comes to you. Clearly you love your grandson. Wish your sons could be more understanding.

Maybe others here will have better words for you today than my poor words. So sorry I don't know how to help.

PS: What is that thing flight attendants say? First put on your own oxygen mask and then help others who need it with theirs.